The field of blood processing primarily comprises hemodialysis and plasmapheresis, although other forms of blood treatment may also be used, for example, hemoperfusion, passing blood through adsorbent cartridges, and the like. To accomplish this, blood sets are used to convey blood from the patient to a blood processing device, and then to return the blood from the device back to the patient. The former blood set is called the arterial set, while the latter set is called the venous set.
In combination, the arterial and venous sets comprise several yards of tubing, and thus are rather cumbersome to handle. Furthermore, cost is of course a critical matter, especially when a patient has a chronic need for treatment as in hemodialysis, so that even small cost savings can add up to a substantial amount over a year or more of repeated usage of disposable arterial and venous sets.
Furthermore, priming of the sets is an issue requiring the skilled attention of technicians, so that any improvement or simplification in the priming process, and other processes of use of the arterial and venous sets, can be valuable.
By this invention, numerous improvements to conventional arterial and venous blood sets are provided for reduction of cost and improved ease and efficiency of use.
By this invention, a combined arterial and venous blood tubing set may be provided for the transport of blood between a patient and a blood processing unit. The combined set comprises an arterial set component which comprises arterial tubing having an arterial patient connector at one end and an arterial unit connector at the other end. A venous set component of the set comprises venous tubing having a venous patient connector at one end and a venous unit connector at the other end.
In accordance with this invention, the arterial and venous patient connectors, and the arterial and venous unit connectors, are respectively substantially and releasably directly connected to each other in such manner that the arterial and venous set components cooperate to form a loop.
This facilitates the installation of the-sets into a hemodialysis machine, for example, resulting in greater ease of installation with a saving of time. Eventually, the set components wind up serving in the normal manner of arterial and venous sets. Even with a relatively small increase or improvement in ease and time saving, the improvement can be quite substantial particularly in the treatment of chronic conditions, as in most hemodialysis, so that the effect of the improvement in time savings can add up to a substantial amount over the course of a year.
Particularly, the arterial and venous unit connectors may be directly connected together with a frangible seal, to permit their breaking apart after the combined set has been primed, for subsequent connection to a blood processing unit.
Thus, the fully primed arterial and venous sets may be directly connected to a reused dialyzer. Solution may then be circulated through the system with air being removed from the dialyzer, but no air being sent to the dialyzer through the primed sets, which reduces the number of air bubbles being trapped within the dialyzer itself. Air coming from the dialyzer will then be typically removed by a bubble trap in the sets, so that it is not recirculated again to the dialyzer.
By this invention, particularly wet, reused dialyzers (or other blood processing devices) can be effectively primed to exhibit improved performance because of a reduced number of trapped air bubbles within the membrane system of the dialyzer.
The arterial and venous patient connectors of the respective arterial and venous sets may optionally be substantially directly connected together by an interconnector tube to permit circulatory priming of the arterial and venous sets, and also to avoid the need of other end closures at the arterial and venous patient connectors, if the arterial and venous sets are supplied to the user in interconnected form as in this invention.
The interconnector tube preferably comprises a tube having a connector such as a female luer connector at each end, for connection with the patient connectors of the arterial and venous sets. Also, the tube may have an attached, integral cap to close an end of the tube after disconnection of one of the patient connectors. Thus, one of the patient connectors may have its sterility preserved while the other patient connector is being attached to a fistula set and access to the patient""s bloodstream is being obtained.
Priming of the connected arterial and venous sets can be performed in a manner similar to that disclosed in Utterberg U.S. Pat. No. 5,951,870, preferably with the modifications described below:
The arterial and venous sets respectively preferably have the substantially directly connected end connectors to form a closed loop as described above. One may pass priming solution into and through a portion of the directly connected arterial and venous sets in a first direction that is reversed to the normal direction of blood flow through the sets, while removing air from one of the sets through a branching port from one of the sets.
One also may pass priming solution into a second direction of flow opposite to the first flow direction through the system (which opposite direction is the normal direction of flow through the system) while continuing to remove air from the system through the port, until substantially all air desired is removed from the arterial and venous sets.
Thereafter, with the flow stopped temporarily the unit arterial and venous connectors are separated and connected to the blood processing unit such as a dialyzer preferably with the blood outlet at the top to facilitate bubble removal. One then pumps the priming solution through the arterial and venous sets and the blood processing unit in the second flow direction (i.e., the normal flow direction which is reversed to the first flow direction), to flush the sets and blood processing unit, without passing substantial amounts of air into the blood processing unit.
This method can be accomplished while pumping the solution with a flow pump such as a roller pump through the set, which operates in only a single, pumped flow direction throughout the entire priming process, the normal, second flow direction described above. The first flow direction, which is reverse to the second flow direction, may take place by gravity flow if desired. Preferably, the arterial and venous patient connectors are substantially directly connected together throughout substantially all of the performance of the above method.
The invention also pertains to a tubular medical fluid set having an in-line bubble trap chamber having a top wall. The top wall defines a port which communicates with flow tubing of the tubular set. The port communicates with a port tube which extends into the chamber and has a tube end which is spaced below the top wall, and preferably below the intended blood/air interface. The tube end defines a wall that directs flow out of the tube circumferentially into and through the bubble trap chamber. Thus, blood entering the chamber through the tube is directed circumferentially about the chamber wall, the effect of which is to direct bubbles radially inwardly, rather than downward.
The chamber also preferably defines a baffle to convert circumferential flow into turbulent flow at positions above the tube end wall and the circumferentially directed blood and at the blood-air interface. This prevents formation of a blood whirlpool having a significant, centrally depressed upper surface. Thus, the centrally disposed bubbles will rise to the top of the chamber to join an air space that is typically present there, without being sucked downwardly as would be caused by the presence of such a blood whirlpool having a centrally depressed upper surface.
Accordingly, the flow pattern of blood near the top of the bubble trap chamber described comprises a top segment of largely turbulent blood flow, and a lower segment of largely circumferential blood flow.
As another aspect of this invention, priming of a tubular medical fluid set may take place, the set having an in-line bubble trap chamber, preferably on the venous set. One passes priming solution into the tubular set preferably at a point pre-pump on the arterial set and bubble trap chamber, while withdrawing air from the set through a port in an upper portion of the chamber. The port communicates with a port tube extending into the chamber in positions which are spaced below a top chamber wall.
Further in accordance with this invention, preferably the in-line bubble trap chamber has an upper portion which defines a port that communicates with the exterior. The port communicates with a port tube extending into the chamber, having a port tube opening spaced below the top wall within the chamber, to automatically define a predetermined air volume and liquid level in the chamber approximately at or above the tube opening as the tubular set is filled with priming solution.
The bubble trap chamber top wall also may define an axially depressed portion which, in turn, defines a needle pierceable, resealable injection site to permit an injection needle of at least about xc2xd inch needle length to penetrate said injection site and to communicate with liquid below said liquid level which preferably is set by the port tube arrangement mentioned above. contrary to the prior art, this injection site carried on the top wall of a bubble trap chamber resides at a lower position from other portions of the top wall, providing a desired inner volume under the other portions for air above a liquid level. In combination with this, the resealable injection site is carried on the axially depressed portion of the top wall, so that the injection site is closer to the liquid level within the bubble trap chamber, preferably permitting an injection needle of at least about xc2xd inch needle length to penetrate the injection site and to communicate with the liquid below the liquid level, while still permitting an air volume within the bubble trap chamber of preferably at least about 4 cc. This permits direct access to the blood by a conventional hypodermic needle from the top of the chamber, for blood sampling from the chamber injection site, permitting infusion of the very expensive drug erythropoietin (xe2x80x9cEPOxe2x80x9d), with pump flushing of the needle several times, drawing blood into the needle and out again to rinse all possible EPO into the set and then the patient, to avoid wasting of the highly valuable material.
Further in accordance with this invention, a tubular blood set for transfer of blood between a patient and a blood treatment device has main blood flow tubing and a flexible branch tube connected in branching relation to the main tubing. The branch tube is adapted for connection at its other end to a source of physiological, cell-free solution, as is conventional.
As particularly shown in Utterberg et al pending patent application Ser. No. 09/203,274, filed Dec. 1, 1998, some of the blood passing through the main blood flow tubing may extend into the branch tube to form a blood-solution interface, so that a pressure monitor which is also connected to the branch tube is protected from contact with blood by the presence of an amount of cell-free solution in the branch tube and a non-compressible, air-free pressure sensing path is provided through the cell free solution and the blood across the interface.
In accordance with this invention, to suppress pressure pulses from the main blood line tending to disrupt the blood-solution interface, a portion of the flexible branch tube is equipped with pulse suppression means. Such means may comprise a partially collapsible portion of the branch tube, a ball valve, a duckbilled valve or the like. The required aspects of the flattened tube or valve are that relatively unrestricted flow is allowed from an attached saline bag to the bloodline but flow from the blood line to the branch tube is suppressed progressively as the negative pressure in the blood line increases. To preferably accomplish this, the pulse-suppressing portion of the flexible branch tube is substantially flattened. Accordingly, this tube portion has a lumen that can and does reduce its cross-sectional area responsive to negative pressure in that area to a degree substantially greater than cylindrical tubing. This results in the suppression of negative pressure pulses created by the pumping of blood through the main flow tubing, which negative pressure pulses tend to disrupt the blood-solution interface in the branch tube. However, if the tube portion that is flattened is preferably placed in the branch tube between the blood-solution interface and the main blood flow tubing, the effect of these negative pressure pulses is damped at the interface area. However, the tube portion, or an alternative valve, can increase its cross-sectional area at any time responsive to positive pressure. Thus, if there is an urgent need to provide saline solution to the extracorporeal blood flow path in the event of a crisis, the tube portion or valve can expand back to its normal cylindrical shape or seating of the valve is less, so that increased solution flow can pass therethrough.
The flattened branch tube portion may comprise a flattened lumen cross section that defines a periphery having at least one open groove, which is transverse to the cross section, to avoid complete closing of the branch tube under negative pressure. Furthermore, a generally cylindrical, flexible branch tube may be used, the tube being flattened at the tube portion by a removable slide clamp which comprises a pair of arms defining a slot between them. The tube portion resides in the slot and, as is preferable, at least one of the arms defines a transversely extending groove that forms the open groove in the tube portion.
Further in accordance with this invention, a protector for a female luer connector is provided, which comprises: an outer sleeve, a central transverse wall defined in the outer sleeve, a male luer projecting axially within the sleeve from the transverse wall to engage the female luer connector along with the sleeve. A tube projects axially within the sleeve from the transverse wall into the direction opposed to the male luer. The tube and the male luer have connected lumens, with the tube having an outer end that is substantially recessed within the sleeve.
Accordingly, a female luer connector may be used as a air venting and/or drain line during priming, for example, with accordance with the teaching of Utterberg U.S. Pat. No. 5,951,870. However, after priming, rather than closing off this line it can be used for the addition of supplemental medication, added solution, or the like because the female luer connector on the end can have its sterility retained by the protector of this invention.
Specifically, the protector of this invention has an outer sleeve inner wall which has screw threads or preferably is free of screw threads. The sleeve inner wall preferably defines axially extending ribs at least on the side of the transverse wall that carries the male luer, to facilitate axially sliding connection and retention with the female luer connector. Furthermore, it is preferred for the tube outer end, which does not need to carry a taper like a male luer, to terminate at a point no more than about two thirds of the distance from the transverse wall to the end of the outer sleeve which is opposed to the male luer, so that this tube serves as a spout for the venting of air and priming solution, and is retained in aseptic condition, since it is recessed in the outer sleeve and thus protected.
Also, it is preferred for a hinged cap to be attached to the outer sleeve in a position which permits closure of the cap over the outer sleeve end that is opposed to the male luer , for preservation of aseptic conditions between priming and subsequent use of the female luer connector.
Thus, sets for blood processing are provided which exhibit significant distinction and advantage over the prior art.